Snap switch



Sept. 3, 1946. MQF LL 2,407,089

SNAP SWITCH Filed May 18. 1944 -2 Sheets-Sheet 1 m 16 61:02, z aaw r R. J. M FALL SNAP SWITCH Filed May 18, '1944 Sept. 3, 1946.

2 Sheets-Sheet 2 Patented Sept. 3, 1946 UNITED STATES PATENT OFFICE 10 Claims. 1

This invention relates to snap switches, and more particularly to switches of the type constructed of resilient sheet metal.

The present application is a continuation in part of my prior co-pending application Serial No. 162,056, filed September 1, 1937, now Patent No. 2,352,215, dated June 2'7, 1944.

The general object of the invention is to provide a snap switch of exceptionally simple construction, and which may be readily operated either manually or by any suitable actuating device.

A specific object is to provide a snap switch consisting of but a single piece or strip of metal, and so constructed that pressure applied to one end causes the other end to move, to open or close a circuit.

A still further object is to devise improved thermally operated means for actuating such a switch.

In order that the invention may be readily understood, reference is had to the accompanying drawings forming part of this specification, and in which:

Fig. 1 is a front view of my improved switch member itself;

Fig. 2 is an edge view thereof, partly in section;

Fig. 3 is a diagrammatic view illustrating one manner in which my improved switch may be employed, and showing my novel thermally operated means for actuating the same;

Fig. i is a similar View, showing magnetically operated means for actuating the switch;

5 is a diagrammatic view showing another thermally operated means for actuating the switch;

Fig. 6 is a similar view showing pressure operated means for actuating the switch;

Fig. '7 is a diagrammatic view illustrating manual means for operating the switch, parts being shown in dotted lines; and

Fig. 8 is a view similar to Fig. 3, parts being omitted, and showing a somewhat modified arrangement.

So far as concerns the switch itself, and the actuating means therefor, Figs. 1, 2 and 3 are identical with figures contained in the drawings of my said prior co-pending application.

Referring first to Figs. 1 and 2, I have attempted to illustrate in detail the construction of my improved snap switch member itself. It consists of a thin, flat strip I, made of springy material, such as bronze, and at a suitable point intermediate its ends I make a hole 2, and deform or upset the material immediately surrounding this hole as by hammering or pressing so as to form a kind of bulge or cup 3. In other words, the material is spread out in this area, and thus, confined by the surrounding material, is placed under strain. It will be understood that the strip is, in actual practice, relatively much thinner than shown in Fig. 2, and that the bulge may not be so deep. When the bulged or strained portion of the strip is however clamped tightly as, for example, against a fixed support, such as 4, by means of a screw 5, as shown in Fig. 3, it develops the peculiar property of snapping suddenly from side to side when moved laterally. Furthermore, instead of being like a pivoted lever, in which opposite ends move in opposite directions, the opposite ends of my improved resilient strip move in the same direction. lhus, when the lower end is pushed toward the right, the upper end snaps over to the right, and vice versa. In Fig. 3, I have shown the movement and bending or bowing of this strip as somewhat eXaggerated for the sake of clearness.

It will, of course, be understood that the head of the screw 5 is relatively small, as compared with the bulge 3 so as to permit the metal in the region immediately surrounding the screw head within the bulge to freely move or buckle. It will be further understood that, as one end of the strip I' is moved laterally, it finally reaches a position where the bulge is caused to suddenly re-- verse, relative to the: body of the strip, shifting from one side to the other, thus throwing both ends of the strip in the same direction, with a snap action.

In Fig. 3, I have shown an improved thermally operated switch actuating means or thermo-electric' relay. I

This improved thermo-ele'ctric relay comprises a pair of bi-metallic strips 6 and l, mounted in any suitable way at one end to a fixed support as indicated at Sa'and 9a. The other end of each of the strips is bent inwardly toward the other strip, so that the free ends are substantially in alignment.

My improved snap switch member 5 is positioned between the two strips 6 and I, generally parallel therewith. The ends of the bi metallic strips 6 and l are adapted to engage the strip I at a point below the support l, and to push the strip one way or the other, at this point. As above explained, this has the effect of causing the upper'end to snap over in the same direction in which the lower end is pushed.

' The upper end of the stri or switch I is adapted to engage contacts 8 and 9, connected respectively with the ends or windings II] and II, which encircle the respective bi-metallie strips 6 and I. The opposite ends of the windings II) and II are connected to binding posts which are connected by Wires I2 and I3 to the opposite contact points I4 and I5 of the usual thermostat I6. The bi-metallic strip of the thermostat I6 is connected by wire II with one side of a transformer I8, the other side of which is connected by wire 49 with the screw 5. The primary of the transformer I8 is connected with a suitable source of alternating current 2|, 22. From one side 25, of this source, extends a wire 23 to a motor 24, which may be the motor of a stoker or oil burner.

The circuit of motor 24 is controlled by a spe-' cial contact 26 carried by but insulated from the lower end of the spring strip I. This contact is adapted to engage a fixed contact 21, which is connected by Wire 28 directly with the other side of the supply circuit, at binding post 22.

The snap switch I is shown in full lines in the position to which it has been moved by the last operation of the thermostat It, namely, an operation which moved the snap switch I to a position in which it opened the circuit of motor 24.

Should the building become too cool and the thermostat I5, answering the demand for more heat, move over into engagement with the left hand contact I4, a circuit will be established from one side of the transformer through wire Iil to the snap switch I, thence to contact 8, through the winding IE], wire I2, thermostat I8, and wire II, back to the transformer. Current flowing through this circuit will cause the Winding I0 1 over a certain distance, the strip will snap into dotted line position, thus closing and holding closed the motor circuit at 21, and at the same time breaking contact at 8 and closing it at 9. The breaking of the contact at 8 stops the cur rent flow through the actuating or heating coil I0, which caused the operation, and at the same time prepares a circuit through the other heating coil I I, ready for the next operation. The motor circuit being closed at 21, the motor 24 will operate to feed coal or oil to the furnace and at the same time supply air thereto until the desired heat has been produced. When the term perature rises to the desired point, the thermostat IB engages the right hand contact I5, thus closing the circuit through the heating coil II, and causing the bi-metallic strip 1 to push the snap switch I back into full line position again, thus opening the motor circuit and allowing the burner to be idle.

An advantage of my improved thermo-electric relay above described is that it operates as a time delay device. If the house thermostat closes at I4 (say), thus causing current to flow through heating coil I0, this current must persist for an appreciable length of time before the bi-metallic element 6 heats up enough to expand sufliciently to kick the switch over. By this means, a momentary closing of the circuit at I4, due to vibration, or to a gust of cold air as from a suddenly opened door, has no effect on the mocluding the heating capacity of the windings,

the length and mass of the bi-metallic strips, and

the distance they must move in order to operate the switch. By varying these factors, a relay can be designed to operate on almost any desired time interval. Moreover, by providing adjustments for the contacts, the delay period of any given relay may be varied considerably.

Referring now to Fig. 4, I have shown electromagnets I0 and II for operating the switch or relay instead of the heating windings I0 and II of Fig. 3. Otherwise, the arrangement is the same, except for the time delay feature, and the parts are similarly numbered. Fixed contacts 8' and 9' are arranged to be engaged by the switch member I and control the circuits through the electro-magnets II' and I0 respectively.

In Fig. 5, I have diagrammatically illustrated an arrangement in which my improved snap switch I may be actuated directly by a thermostatic element subjected to the temperature of the ambient atmosphere. In this figure, the motor 24 is supplied with current through leads 29 and 3I, and its circuit is controlled at a contact 30, arranged to be engaged by the switch member I.

A thermostatic device in the nature of an expansible bellows is illustrated at 32 and a rod 33 extends from this bellows and is provided at its end with a yoke 34, which loosely engages over the lower end of the switch member I. If we assume that, in this case, as before, the motor 24 operates a Stoker Or oil burner for heating the premises where the thermostatic element 32 is located, then when the temperature has risen to the desired point, this thermostatic element expands, thus pushing laterally the lower end of the switch element I over to the position illustrated in dotted lines. As above explained, this causes the upper end of the switch element to also snap over into dotted line position, thus opening the motor circuit. When the temperature falls too low, the bellows 32 contracts, thus moving the switch back to full lin position again and again closing the motor circuit.

In Fig. 6, I have shown a similar arrangement, but arranged to be controlled by a fluid pressure responsive device. This is also indicated as a bellows 32', supplied with fluid through a pipe 35. In this case, the motor 24 might operate a pump or compressor. When the pressure rises to the desired point, the bellows 3f! expands and pushes over the lower end of the switch element, thus causing the upper end to snap over into dotted line position, thus interrupting the motor circuit.

In Fig. 7, I have illustrated one Way in which my improved switch member may be operated manually. In this figure, I have shown, in dotted lines, the conventional representation of an ordinary lamp socket, the body being indicated at 35, and the threaded shell at 31. The usual push pin is shown at 3B and this is provided with a slot or opening in which the lower end of the switch member I is loosely received, this switch member being anchored at its middle part to a fixed support, by means of the screw 5, as before. In the closed positions shown, the switch member is adapted to engage a contact 39, connected with the threaded shell 31 of the socket. One wire all of the lamp cord is connected to the screw 5. while the other wire 42 is connected to the center contact 4I.

From this, it will be seen that when the push pin 38 is moved toward the right, the lower end of the switch member I will be deflected laterally until a point is reached where the deformed portion buckles, thus causing the upper end of the switch member to snap toward the right also, and thereby disengage the contact 39.

It will be understood that the resilience of the strip I is suiiicient to yieldingly hold the push pin 33 in either of its extreme positions. Thus, in my improved construction, the switch member itself takes the place both of the circuit controlling means and of the spring means usually employed in this type of mechanism.

In Fig. 8, I have shown a slight variation of the arrangement illustrated in Fig. 3. In this modification, the switch member is designated 5', and its lower end is made somewhat shorter than in Fig. 3. The motor controllirr contact 25 is mounted on the upper, instead of the lower end of the switch member, and engages the contact point 22' at the same time that the extreme end of the switch member engages the contact 9, as indicated in dotted lines. This arrrangement gives a somewhat better snap action.

What I claim is:

l. A switch comprising a thin strip of resilient metal, means for anchoring said strip to a fixed support at one point, said strip having a deformed, laterally oiiset area immediately adjacent said anchoring means, and a circuitcontrolling contact associated with said strip.

2. A snap switch comprising a thin strip of resilient metal, means for anchoring said strip to a fixed support at one point, said strip having a deformed, laterally offset area surrounding said anchoring means, and a circuit-controlling contact associated with said strip.

3. A snap switch comprising a thin strip of resilient metal, means for anchoring said strip to a fixed support at a point intermediate its ends, said strip having a deformed, offset area immediately adjacent said anchoring means, a circuit controlling contact near one end of said strip, and means for moving the other end of said strip laterally.

4. A snap switch comprising a thin strip of resilient metal, means for anchoring said strip to a fixed support at a point intermediate its ends, said strip having a deformed, offset area immediately adjacent said anchoring means at both sides thereof, a circuit-controlling contact arranged to co-operate with one end of said strip, and means for moving the other end of said strip laterally.

5. A snap switch comprising a thin strip of resilient metal, means for anchoring said strip to a fixed support at a point intermediate its ends, means for moving one end of said strip laterally, means whereby such movement causes the opposite end of said strip to move in the same direction, and a circuit-controlling contact arranged to be engaged by said strip.

6. A snap switch comprising a thin strip of resilient metal, means for anchoring said strip to a fixed support at a point intermediate its ends, means for moving one end of said strip laterally, means whereby such movement causes the opposite end of said strip to move in the same direction, and a circuit-controlling contact arranged to be engaged by said opposite end of said strip.

'7. The combination with a snap switch comprising a resilient strip anchored at a point intermediate its ends, and having a deformed portion adjacent the point of anchorage, of electrically actuated means for moving one end of said strip laterally, and a contact arranged to be engaged by the other end of said strip for controlling the circuit of said electrically actuated means.

8. The combination with a snap switch comprising a resilient strip anchored at a point intermediate its ends, and having a deformed portion adjacent the point of anchorage, of a pair of electrically actuated means for moving one end of said strip laterally in opposite directions, a pair of contacts to each of which one side of one of said electrically actuated means is connected, and. the other end of said strip being positioned to play between and alternately engage said contacts, and said strip forming a part of the circuit of said electrically actuated means, whereby when the first mentioned end is moved laterally by one of said electrically actuated means beyond a certain position, the other end moves in the same direction with a snap action, thereby disengaging one of said contacts and breaking the circuit through one electrically actuated means, and engaging the other contact and establishing at that point a circuit through the other electrically actuated means.

9. The combination with a snap switch comprising a resilient strip anchored at a point intermediate its ends and being transversely deformed in the region surrounding said anchorage, of a pair of thermostatic elements having free ends adjacent and opposite each other, a heating winding on each of said elements, a pair of contacts to each of which one end of one of said windings is connected, one end of said strip being disposed between and adapted to be engaged and moved by the free end of either one of said elements, and the other end of said strip being positioned to play between and alternately engage said contacts, and said switch forming a part of the circuit of said heating windings, whereby when the first mentioned end is moved laterally by one of said electrically actuated means beyond a certain position, the other end moves in the same direction with a snap action, thereby disengaging one of said contacts and breaking the circuit through one electrically actuated means, and engaging the other contact and establishing at that point a circuit through the other electrically actuated means.

10. The combination with a snap switch comprising a resilient strip anchored at a point intermediate its ends and being transversely deformed in the region surrounding said anchorage, of a pair of thermostatic elements having free ends adjacent and opposite each other, a heating winding on each of said elements, a pair of contacts to each of which one end of one of said windings is connected, one end of said strip being disposed between and adapted to be engaged and moved by the free end of either one of said elements, and the other end of said strip being positioned to play between and alternately engage said contacts, and said switch forming a part of the circuit of said heating windings, whereby when the first mentioned end is moved laterally by one of said electrically actuated means beyond a certain position, the other end moves in the same direction with a snap action, thereby disengaging one of said contacts and breaking the circuit through one electrically actuated means, and engaging the other contact and establishing at that point a circuit through the other electrically actuated means, and an additional independent pair of contacts constructed and arranged to be opened and closed by the lateral movements of said strip.

ROBERT J. MCFALL. 

